320 



KNOWLEDGE 



[KKik 10, 18h. 



London, on Iho otIuT Imnd, OinnkR to tliu cIToriB of tlio Kooipty, 

 thoro wa« nn uin'iii'ciimttHl rmiilniiin wliicli kept the (lincnac iilivo. 

 Tlio opi'leniic hud rtntio to iiH from l''rniico, iinil hn*i arisen thpn* 

 from the iiii«iiiiilur_v e<>ii<litii>n of Iho Krcnc-li aoldicni diirinf; the 

 lato wnr. Iliirin); iv^iirrt to nil tlic circiinislnncpii of tlip fpidrmir 

 nnd from u Htiidy ol i<piili-micH in general, tie Imd no hesitation in 

 Haying that Iho perioil IbTI-^M* was altogether exceplinnnl, and that 

 tho rate of 8n<»ll-pox mortality during that derade afforded no 

 baaix for an argument n;,'ain8t vnceination. Up need only make 

 ono more oliHervation. His op[)onont» would doubtleBS urge that 

 Huch plarrs as Dpwsbiiry. Lpiceater, nnd Koighley, where the nnti- 

 Tnecinationials were strong, had had a eomparative inininnity from 

 small-pox. But Mio truth was, that the diKonso had already died out 

 in those towns, and that the mere disuse or negleet of vaceination 

 ilid not reproduce it. As an illustration of the faet that no sanita- 

 tion woulcl nuflipo to excludo small-pox, the cnso of San Francisco 

 might bo cited. In the Chinese quarter of that city a smouldering 

 tiro of small-jiox had existed for some time, but thoro had been no 

 considcrnblo outbreak since the autumn of the year IS70, when 

 nearly 150 cases occuiTcd in tlio best and richest parts of tho city, 

 in spite of the fact that, a.s tho very low annual dgath-rate showed, 

 the sanitation of the place was singularly good. Of the children, 

 however, all of whom had been vaccinated — many from heifer 

 lymph — only ton or twelve took the disease. 



THE MOON'S BIRTH BY TIDAL 

 EVOLUTIOX. 



IN response to the wishes of many readei's of Kxow- 

 LEDtiE, wc had intended to prepare for these pages a 

 paper on the viow.s to wliich ISIr. G. Darwin has been 

 led, and which Dr. Ball has eloquently expounded, 

 respecting the l>irth of the moon hy tidal evolution. It 

 occurred to us, however, when our essay was nearly com- 

 pleted, that our readers might like to hear Dr. Ball him- 

 self on the suV>ject ; and we now have much pleasure in 

 announcing that ne.xt week a paper from the pen of the 

 Astronomer lloyal for Ireland on the moon's birth by 

 tidal evolution will appear in these pages ; to be followed 

 by another on the astronomical consequences of such 

 evolution. The Editok. 



THE MENACING COMET. 



READERS of Knowledge who have followed my 

 remarks on the various predictions which have been 

 made respecting the approaching end of the world, must 

 have been inclined to e.xclaim : — " Is Saul also among the 

 prophets? " when they heard that, as the Sjyectator tells us, 

 I had definitely indicated the year 1897 as one in which the 

 world would, in all probability, come to an end. I have care- 

 fully read over the essay in my recently-issued " Familiar 

 Science Essays," to see whether it should suggest these 

 startling anticipations ; and I find nothing there which does 

 not seem in perfect accordance with observed facts and 

 scientific deductions therefrom. .\11 that is there said I 

 certainlj' adhere to still. Ifow far it can be regaided as 

 threatening the end of the world in 1897, I shall give the 

 readers of Knowledce an opportunity of inferring next 

 week, when a short article on the comet which is thus — • 

 thinks the Sjifctntor — to bring the world to catastrophic 

 end will appear, illustrated by a picture of that menacing 

 object Pos.sil)ly after reading that article, those who have 

 urged me to reconsider my verdict may find that some 

 chance is still left for our good old earth. 



R. A. Proctor. 



Ebr,ma. — Lines 0, 11, 12. and 13, p. 270, for "wood" road 

 " woad." Line 37, "tsitril" for "nitrite." Lines 39 and 40, 

 for "oitho-nitro phenyl -glyoxnlic" read " ortho-nitro-phcnyl-gly- 

 oxvlic." 



Icttcig to tiK euitor. 



[Thr Editor do*t not hold kimtelfirfwponnhte far thropiniona of kij rorretpont 

 Be cannot undrrtuke fo return manutcript* or to corrr»vond iriik ikrir ttrit**'. 

 eommunieatioHt §knuU be at tkori a* pottible, connstarliy k-i/A J'ult and cUar - 

 mrtitt of the wrifer't m fining.'] 



Alt Kditorial eommttuicationa »hould be addreeifd to the 'Editor of Ksowi.i ■ 

 an Itujtinft commujiicationt to the PubUakert, at the Office^ 7\ Great (^ 

 ttrett, 1F.C. 



AH Jifmitfnncet, Chrqufr, and PoMl-Offtce Order$ nkofi/d be made paualh tn 

 It^nor: Wymnn ir Sons, 



•,* All tfttfra to the Editor tcill be y umbered. For ronvf^nimce of rejerenee, 

 corrfapondrnt», when referring to any letfer^iciU ol'ige by mentioning its number 

 and the poijf on irkich it appear*. 



AU Lrttera or Q'leriee to the Editor tckirh require .i/t*-ntion in f\e enrrenl wue c/ 

 KsovFhKDOK, tkould reach the Publiahing Office not Uterthnn the Saturday preceding 

 the dag qf publication. _^___^ 



" In knovrlrdfre, that man onlv is to be contemneil nnd decked who is not i 



state of transition >'or is there snythini; more adverse to accunox ' 



tlian flxity of opinion." — Faradag. 



" There is no harm in makinc; a mistake, but ^'■at harm in making none. Show 

 me a man ^rho makea no mistakes, and I will show jou a man who has dona 

 nothing." — Liebig. _— ^-— - 



(Bmv CoiifSpontirnrf Columns. 



OUR LETTERS, QUERIES, AND REPLIES. 



[268] — Letters, queries, and replies reach us in such numbers, 

 that not only are we unable to find room for a third of them, but 

 they involve a tax on our time seriously interrupting the progress 

 of more important matters. We are obliged, therefore, to adopt tho 

 following rules : — 



(1.) Letters to have a chance of appearing must be concise; 

 they must be drawn up in the form adopted for letters here, so that 

 they may go untouched to the printers ; private communications, 

 therefore, as well as queries, or replies to queries (intended to 

 appear as such) should be written on separate leaves. 



(II.) Queries and replies should be even more concise tboa 

 letters ; and drawn up in the form in which they are here pre- 

 sented, with brackets for number in case of queries, and the 

 proper query number (bracketed) in case of replies. 



(III.) Letters, queries, and replies which (either because too 

 long, or imsuitable, or dealing with matters which others hare 

 discussed, or for any other reason) c.innot find place here, will 

 either be briefly referred to in answers to correspondents, op 

 acknowledged in a column reserved for the purpose. 



We beg that correspondents will consider how the matter stands. 

 It is essential that each number should contain a certain portion 

 of original matter, illustrations, notes on science and art, short 

 extracts from homo and foreign jotimals, mathematics, and so 

 forth. We cannot yet enlarge Knowi.epgk more than, we have 

 already done ; to compress our correspondence into the space left 

 open for it, by abridging, e.Ktracting, and putting the matter so 

 arranged into proper form for the printers, would require either 

 the whole time of the editor, or the assistance of a staff of sub- 

 editors. Om- correspondents nrast, therefore, do the work of 

 abridgment and arrangement themselves ; at any rate, they must 

 not be annoyed if, failing this, their communications arc wasted. 



To ninety-hundredths of our readers no apology for this notiio 

 need be given. On the contrary, some explanation may lie due i > 

 them for the way in which correspondence has threatened to intii 

 fere with the proper work of Knowledge. The Editok. 



FLESH FOOD. 



[269] — I trust you will allow me to point out in your columns the 

 extreme unfairness of the comparison you suggest between vege- 

 tarians and flesh-eaters. You ask vegetarians to pnxluce a list of 

 famous men of their persuasion eqnal to that which can be made 

 out by their opponents. Now this would bo an excellent and per- 

 feclly fair test, if exactly half the civilised world had always been 

 vegetarians; but as matters actually stand, it is grossly unfair. You 

 might as well ask tho Quakers to make out such a list, or the 

 Albinos, and the test would be just as valuable. Tho list of famons 

 men, if it is to be of any use, must be made out with due regard to 

 the projiortion between vegetarian nnd carnivorous candidates for 

 fame, and from this test the vegetarians have no cause to shrink. 



